**31. **Two divers G and H are at depths 20m and 40m, respectively below the water surface in a lake. The pressure on G is O_{1}while the pressure on H is P_{2}, If the atmospheric pressure is equivalent to 10m of water, then the value of P_{2}/P_{1}is

**A.**0.50**B.**0.60**C.**1.67**D.**2.00

**32. **

The figure above represents a block-and-tackle pulley system on which an effort of W Newtons supports a load of 120.0N. If the efficiency of the machine is 40oo, then the value of W is

**A.**28.0N**B.**48.0N**C.**288.0N**D.**50.0N

**33. **

In an experiment in which molten naphthalene is allowed to cool, the cooling curve i n the figure was obtained. The temperature 80^{o}C is known as the

**A.**cooling temperature**B.**boiling point**C.**melting point**D.**vaporization point

**34. **In the figure, the value of R is

**A.**3Ω**B.**6Ω**C.**4Ω**D.**5Ω

**35. **Which of the following instruments consumes the highest current?

I. Electric iron II. Television set III. Torch light IV. Immersion heater | 250v 220v 6v 110v | 1kW 110W 30W 500W |

**A.**I**B.**II**C.**III**D.**IV

**36. **

In which of the following diagrams is the length of the tube equal to one wavelength?

**A.**a**B.**b**C.**c**D.**d

**37. **A hydrometer is an instrument for measuring the

**A.**a depth of water of water in a vessel**B.**relative density of a liquid by the method of flotation**C.**relative density of a liquid by finding the apparent loss in weight**D.**relative humidity of the air

**38. **A substance has half of 3 min. After 6 min, the count rate was observed to be 400. What was its count rate at zero time?

**A.**1600**B.**1200**C.**200**D.**2400